The present invention is related to the field of controlling mechanical and/or electrical activity of smooth muscle by applying electrical fields to the muscle.
In many body tissues, activity of individual cells, especially contraction, is initiated by changes in trans-membrane potentials. These types of tissue are also called excitable tissue, since when they are excited by an electrical signal, they react by activation. Some examples of excitable tissue include: cardiac muscle, skeletal muscle, smooth muscle and neural tissue. In many cases, the activity of large numbers of such excitable tissue cells is synchronized by propagating electrical activation signals. An activation signal is an electrical signal which, when it reaches an excitable cell, causes it to depolarize and perform its activity. In addition, the depolarization creates a new propagating activation signal which then continues to propagate towards the next un-activated cell. In most excitable tissue, the cell is refractory after a depolarization, such that the activation signal cannot immediately travel backwards.
The gastrointestinal (GI) tract is an example of a major physiological system in which many activities are coordinated by propagating electrical activation signals. The GI tract comprise a stomach, a small intestine and a large intestine. In a typical digestive process, food is chewed in the mouth and enters the stomach for digestion. The food is periodically passed to the antrum for grinding down and then passed back to the stomach. After a period of time, the pyloric sphincter opens and the food is passed to the small intestine. In the small intestine the food is churned and passed forward by a rhythmic motion of the intestines, until it reaches the large intestine. A one way sphincter allows movement only from the small intestine to the large intestine. Once in the large intestine, the food is further churned and compacted by motions of the large intestines. These motions also advance the digested food, now feces, to a pair of outlet sphincters, which mark the end of the GI tract.
The GI tract is mostly composed of smooth muscle, which, when depolarized, contracts. All of the above described movements of the GI tract are synchronized by propagating activation signals. As can be appreciated, in many cases, these electrical signals are not properly activated and/or responded to, resulting in disease. In one example, an ulcer causes inflammation of GI tissue. The inflamed tissue may generate spurious activation signals, which can cause the stomach to contract in a chaotic manner. The inflamed tissue may also affect the activation profile of the stomach by not conducting activation signals or by having a different conduction velocity than healthy tissue.
Pacing the GI tract is well known in the art, for example as shown in U.S. Pat. Nos. 5,292,344 and 5,540,730, the disclosures of which are incorporated herein by reference. The ""730 patent describes both increasing and decreasing the excitability of the GI tract by stimulating different portions of the vagus nerve. The ""344 Patent describes a pacemaker which directly stimulates portions of the GI tract. Electrical stimulation of the GI tract is also known to be used for stimulating the GI tract of patients suffering from post operative damping syndrome, as evidenced by SU 1039506, the disclosure of which is incorporated herein by reference.
The uterus also comprises smooth muscle, which contracts in response to electrical activation signals. xe2x80x9cUterine Electromyography: A Critical Reviewxe2x80x9d by D. Devedeux, et al., Am. J. Obstet Gynecol 1993; 169:1636-53, the disclosure of which is incorporated herein by reference, describes the different types of uterine muscle and electrical signals generated by such muscles. An important finding which is described therein is that electrical activity in the uterus appears to be uncorrelated prior to labor, but when labor is established, the contractions and the electrical activity associated to them become highly synchronized.
In current medical practice, labor can be delayed by administering certain drugs. However, the operation of these drugs is somewhat uncertain. In addition, labor can be induced using other drugs, such as Oxytocin. Unfortunately, the dosage of Oxytocin which is required cannot be known in advance and overdoses of the drug can result in over-contraction which can mechanically damage the fetus and/or the mother.
SU 709078, the disclosure of which is incorporated herein by reference, describes stimulating the uterus after labor using an externally applied electrical current, to increase the contractions and aid in the expulsion of the afterbirth and reduce bleeding by rapidly shrinking the uterus.
The use of locally applied electrical fields for reducing pain is well known in the art. xe2x80x9cElectrical Field Stimulationxe2x80x94Meditated Relaxation of a Rabbit Middle Cerebral Arteryxe2x80x9d, D. A. Van Ripper and J. A. Bevan, Circulatory Research 1992; 70:1104-1112, the disclosure of which is incorporated herein by reference, describes causing the relaxation of an artery by applying an electric field. U.S. Pat. No. 4,537,195, the disclosure of which is incorporated herein by reference, describes treatment of pain using TENS (Transcutaneous Electrical Nerve stimulation), for treatment of headaches. It is hypothesized in this patent that the electrical stimulation prevents the constriction of arteries by stimulation of the muscle in the walls of the arteries, thereby preventing the dilation of capillaries, which dilation is a cause of headaches.
SU 1147408, the disclosure of which is incorporated herein by reference, describes a method of changing the distribution of blood flow in and about the liver, by applying electrical fields to arteries, varying the frequency of the field in synchrony with the cardiac rhythm.
U.S. Pat. No. 5,447,526, the disclosure of which is incorporated herein by reference, describes a transcutaneous electrical smooth muscle controller for inhibiting or decreasing the contraction of smooth muscle, especially uterine muscle. The controller, which is applied to the outside of the abdomen may also sense muscle contractions and effect inhibitory or stimulatory pulses unto the uterus as a whole, depending on the medical application, in response to sensed contractions.
It is an object of some aspects of the present invention to provide a method of directly and locally controlling the contraction and/or force of contraction of smooth muscles. Such control is especially employed, in particular preferred embodiments of the invention, in the gastrointestinal (GI) tract, the uterus, the bladder, endocrine glands, the gall bladder and blood vessels.
The inventors have found that the force of contraction of a smooth muscle can be both increased and decreased by a judicial application of a non-excitatory electric field. A non-excitatory electric field is an electric field which does not induce a propagating action potential in the smooth muscle. Such a non-excitatory electric field does, however, modify the reaction of the smooth muscle to an excitatory field. The inventors have also found that it is possible to desensitize smooth muscle to an activation signal, thereby the desensitized smooth muscle does not respond to an activation signal and also does not propagate the activation signal. Shortly after the field is removed, its effects are undone. It should be appreciated that many smooth muscles are characterized by multiple layers of fibers, the fibers in each layer having a preferred orientation. In a preferred embodiment of the invention, individual layers are selectively controlled by applying the electric field to be substantially parallel to the fiber orientation (in which case the field is highly effective). When a lesser degree of interaction between the muscle layer and the field is desired, the field is preferably applied perpendicular to the muscle fibers.
It is an object of some embodiments of the present invention to provide a method of more precisely controlling the GI tract than is possible using drugs and/or single or multi-site pacing. In a preferred embodiment of the present invention, the force of contraction of a portion of the GI tract is increased, such as to compensate for weakened contraction and/or to advance an otherwise stuck bolus. Alternatively or additionally, the force of contraction may be reduced, such as to treat a patient with overly sensitive intestines. Alternatively or additionally, a section of the intestines may be desensitized or blocked from electrical activation signals in order to promote the healing of a lesion in the section. Reducing or blocking contraction is also useful in treating acute diarrhea and to stop leakage from a stoma, when such leakage is undesired. Additionally or alternatively, the activation profile of the GI tract, which normally includes a forward moving wave and a returning wave, is changed, for example, by blocking the returning wave (the reflux), so as to increase the motility of the intestines. Blocking the returning wave may be performed by desensitizing one or more segments of the intestines after the forward wave has passed, so that the returning wave will be stopped at the desensitized segment. Alternatively, the entire length of the intestines is desensitized for the duration of the returning wave. After the returning wave is stopped, the desensitizing field is preferably stopped so as to allow the forward wave to properly propagate. The forward and returning waves can be detected either by their mechanical activity or, more preferably, by their electrical activity.
In a particular preferred embodiment of the present invention, the tension of the lower end of the colon is reduced so as to improve local blood supply and aid in the healing of hemorrhoids and anal fissures. It has recently been suggested that much of the pain associated with hemorrhoids is caused by ischemia of the tissue, which in turn, is caused by abnormally increased tension of the lower colon. Such tension has been hereunto been treated using topically applied drugs, such as nitroglycerin.
An endoscope, in accordance with another preferred embodiment of the present invention, locally controls the activity of the intestines so as to cause the smooth muscle to advance and/or retreat the endoscope. Alternatively or additionally, local electrical desensitization is used as a replacement and/or in addition to relaxation of the bowels using drugs.
Although some of the embodiments of the present invention have been described with respect to an endoscope or a colonoscope, these embodiments of the invention should be understood to apply to invasive probes in general and to endoscopes, colonoscopes, hysteroscopes and rectoscopes, in particular.
It is an object of another preferred embodiment of the present invention to provide a method of more precisely controlling labor, including, delaying and/or advancing the onset of labor, increasing or decreasing the length of labor and/or stopping labor from proceeding after it has started or when it is still in the pre-labor stages. Stopping labor is especially important for treating cases of pre-term onset of labor. Such control is exerted, in accordance with a preferred embodiment of the invention, by reducing the contractility of the uterine muscles, increasing their contractility or by desensitizing them so that synchronized contractions cannot occur. It is hypothesized that labor is a self-feeding process, where increased forces of contraction generate even stronger forces of contraction in the next contraction cycle. By damping the contraction force, such a feedback loop can be broken. In addition, when the uterus is desensitized, contractions cannot occur and labor is at least temporarily stopped, without significant danger to the fetus, as might be expected from drugs. Labor interrupted in this way can be rapidly restarted, without the problems associated which drug-terminated labor. In a preferred embodiment of the invention, spurious electrical activation signals arising from anomalous portions of the uterus, such as fibroid containing portions, which activation signals may cause premature labor, are reduced by local desensitizing and/or blocking of the uterine tissue.
It accordance with another preferred embodiment of the invention, menstruationally meditated contractions of the uterus (cramps) are treated by detecting such cramps and applying a desensitizing electrical field to the uterus to damp such cramps. Alternatively, such a desensitizing electric field may be applied during the time when such cramps may be expected to occur.
An object of another preferred embodiment of the present invention is to control the contractility of the bladder. In one preferred embodiment of the invention, the bladder is desensitized such that it does not spontaneously contract when such contraction is undesirable. Preferably, an apparatus for controlling the bladder in accordance with a preferred embodiment of the invention, includes a feedback mechanism, which stops its activity when the bladder becomes over full. In an additional or alternative embodiment of the invention, the force of contraction of the bladder is increased during urination. In a preferred embodiment of the invention, the force of contraction of the bladder is increased in patients having bladder hypertrophy, so that the bladder will gradually shrink. Such treatment is preferably combined with drug treatment and/or an implantation of a stent, which treatments may be used to reduce blockage of the urethra.
In accordance with another preferred embodiment of the invention, the output rate of endocrine or neuro-endocrine glands is controlled, preferably reduced, by applying a desensitizing electric field. In a preferred embodiment of the invention, a desensitizing electric field is applied to the beta islet cells of the pancreas, so as to reduce insulin generation in patients suffering from hyper-insulinemia levels. Preferably, such control is applied without measuring the electrical activity of the beta islet cells. Alternatively or additionally, such control is applied while monitoring the blood glucose level. The desensitizing field is preferably a locally applied DC field, whose polarity is switched at a very low frequency, such as once an hour, so as to avoid polarization of the electrodes and/or damage to the tissue.
Another aspect of the present invention relates to treating vascular spasm, angina pectoris and/or abnormal blood pressure, by electrically controlling large blood vessels in the body. In accordance with a preferred embodiment of the invention, large veins, such as the abdominal veins are relaxed by applying a local inhibitory electric field to them. Alternatively or additionally, large arteries, such as the aorta, are relaxed by applying a local inhibitory electric field to them. Alternatively or additionally, excitatory fields are applied to the arteries and/or veins so as to constrict them. As can be appreciated, changing the volume of the arteries and veins can directly affect a patient""s blood pressure and/or cardiovascular performance. In addition, relaxing the veins reduces the preload to the heart, which can stop an episode of ischemia, e.g., angina pectoris. Further, relaxing the aorta is useful in cases of vascular spasm, which, in many cases, is the cause of angina pectoris.
The relaxing electrical field is preferably applied to the blood vessels in spasm, which, in some cases, may be coronary blood vessels. Electrically induced relaxation of blood vessels may be used instead of or in addition to pharmaceuticals. Further, forced relaxation of arteries and veins is useful for treating an acute ischemic event. Typically, the ischemic event causes increased heart rate which further strains ischemic cardiac tissue. By reducing the preload and/or the afterload of the heart, the cardiac demand is reduced, which reduces the oxygen demand of the ischemic tissues and/or allows better perfusion of the ischemic tissues. Additionally or alternatively, the diastole may be extended to aid the perfusion of the cardiac muscle. Extending the diastole may be achieved, for example, by desensitizing at least a portion of the heart. using techniques, such as described in PCT IL97/00012, xe2x80x9cElectrical Muscle Controllerxe2x80x9d, filed on Jan. 8, 1997, the disclosure of which is incorporated herein by reference.
There is therefore provided for, in accordance with a preferred embodiment of the invention, a method of promoting the healing of a lesion in a smooth muscle, comprising:
selecting a smooth muscle portion having a lesion; and
applying a non-excitatory electric field to the portion, which field reduces the mechanical activity at the portion.
Preferably, applying an electric field comprises desensitizing the smooth muscle portion. (Alternatively or additionally, applying an electric field comprises blocking the electrical activity of smooth muscle surrounding the lesion.
Preferably, the lesion is an ischemic portion of the muscle. Alternatively or additionally, the lesion is a sutured portion of the muscle.
Preferably, reducing the mechanical activity comprises inhibiting mechanical activity at the location.
In a preferred embodiment of the invention, the smooth muscle portion is part of a gastrointestinal (GI) tract.
There is also provided in accordance with a preferred embodiment of the invention, a method of treating diarrhea, comprising:
selecting a portion of irritated intestine; and
applying an electric field to the portion, which field reduces the mechanical activity at the portion.
There is also provided in accordance with a preferred embodiment of the invention, a method of treating obesity, comprising:
selecting at least a portion of a stomach; and
applying an electric field to the portion, which field delays or prevents the emptying of the stomach.
There is also provided in accordance with a preferred embodiment of the invention, a method of treating nausea, comprising,
selecting at least a portion of a stomach; and
applying an electric field to the portion, which field reduces the mechanical activity of the stomach.
There is also provided in accordance with a preferred embodiment of the invention, a method of controlling emptying of a stoma, comprising:
applying an electric field to an exit portion of the stoma, which field reduces the motility of the end portion; and
removing said field when emptying of the stoma is desired.
Preferably, the method further comprises applying a second electric field to the exit portion, which second field increases the motility of the stoma, when emptying of the stoma is desired. The second field may be an excitatory field. Additionally or alternatively, the second field is one which increases the force of contraction.
There is also provided in accordance with a preferred embodiment of the invention, a method of treating a hemorrhoid, comprising:
providing a patient having a colon; and
applying an electric field to a portion of the colon, which field relaxes at least a portion of the colon, near an exit therefrom.
Preferably, the hemorrhoid is not situated at said portion of the colon. Alternatively or additionally, the method comprises:
measuring a tension in the portion of the colon,
wherein applying an electric field comprises applying an electric field when the measured tension is above a predetermined amount.
In a preferred embodiment of the invention, in a method a described above, applying an electric field comprises applying the electric field at a delay after a local activation time.
There is also provided in accordance with a preferred embodiment of the invention, a method of increasing the motility of a GI tract, comprising:
selecting a portion of the GI tract; and
applying a non-excitatory electric field to the portion, which field increases the force of contraction at the portion.
Preferably the method includes applying a second electric field to a second portion of the GI tract, downstream from said portion, which second electric field decreases the force of contraction at the second portion.
There is also provided in accordance with a preferred embodiment of the invention, a method of increasing the motility of a GI tract, comprising:
determining a timing of a returning wave in the GI tract; and
applying an electric field to at least a portion of the GI tract, which electric field reduces the response of the GI tract to the returning wave.
Preferably, determining a timing comprises detecting a forward wave and wherein applying an electric field comprises applying an electric field only at times where it does not substantially interfere with the forward wave.
Alternatively or additionally, determining a timing comprises detecting a returning wave and wherein applying an electric field comprises applying an electric field only at times where it substantially interfere with the returning wave.
Alternatively or additionally, applying an electric field comprises applying an electric field which inhibits the propagation of an activation signal, which activation signal synchronizes the returning wave.
Alternatively or additionally, applying an electric field comprises applying an electric field which reduces the force of contraction in at least a portion of the GI tract.
There is also provided in accordance with a preferred embodiment of the invention, a method of selectively exciting only a layer of muscle in a smooth muscle having a plurality of muscle layers, each with a different fiber orientation, comprising:
applying an inhibitory electrical field, parallel to the a fiber orientation of a first layer of muscle, to the muscle; and
applying an excitatory electric field to the muscle, which electrical field excites a second layer of the muscle.
There is also provided in accordance with a preferred embodiment of the invention, a method of selectively increasing the force of contraction of only a layer of muscle in a smooth muscle having a plurality of muscle layers, each with a different fiber orientation, comprising:
applying an inhibitory electrical field, parallel to the a fiber orientation of a first layer of muscle, to the muscle; and
applying a second electric field to the muscle, which second electric field is oriented parallel to the fiber orientation of a second layer of muscle and which second field increases the force of contraction in the second layer of muscle.
There is also provided in accordance with a preferred embodiment of the invention, a method of multi-point pacing for a smooth muscle, comprising:
applying excitatory electric fields at a plurality of locations on said muscle; and
applying at least one inhibitory electric field at a second plurality of locations, situated among said plurality of locations, wherein said inhibitory electric field prevents the propagation of an activation signal between said first plurality of paced locations.
There is also provided in accordance with a preferred embodiment of the invention, apparatus for controlling at least the local activity of a portion of an in vivo smooth muscle, comprising:
a plurality of electrodes, adapted to be in contact with a portion of smooth muscle to be controlled; and
a controller which electrifies said electrodes with an electrical field which does not generate a propagating action potential in the smooth muscle, which electrical field modifies the reaction of the smooth muscle to an activation signal.
Preferably, the apparatus includes an electrical activity sensor which detects electrical activity at the portion and wherein said controller electrifies said electrodes responsive to signals from said sensor. Preferably, the controller electrifies each of said electrodes is responsive to its local electrical activity. Additionally or alternatively, the electrical activity sensor senses electrical activity through ones of said plurality of electrodes.
Alternatively or additionally, the apparatus includes an impedance sensor, which senses at least one impedance between selected ones of said plurality of electrodes.
Alternatively or additionally, the apparatus includes a force transducer which detects mechanical activity at the portion and wherein said controller electrifies said electrodes responsive to signals from said sensor. Preferably, said controller applies an inhibitory electric field to the muscle, when said mechanical activity is above a certain threshold. Alternatively or additionally, the electrification at each of said electrodes is responsive to its local mechanical activity.
Alternatively or additionally, the non-excitatory field inhibits mechanical activity at the portion. Alternatively or additionally, the non-excitatory field reduces the force of contraction at the portion. Alternatively or additionally, the non-excitatory field increases the force of contraction at the portion. In a preferred embodiment of the invention, the controller electrifies at least one of said electrodes with an excitatory electric field.
In a preferred embodiment of the invention, the plurality of electrodes are arranged in a two-dimensional matrix.
Alternatively or additionally, the controller selectively electrifies ones of said plurality of electrodes to selectively generate one of two perpendicular electric fields.
In a preferred embodiment of the invention, the controller is adapted to be implanted inside a stomach and attached to the stomach wall.
Alternatively or additionally, the apparatus is adapted to be implanted inside a uterus and attached to the uterus wall.
Alternatively or additionally, the apparatus is adapted to be implanted inside the body and outside a portion of the GI tract.
Alternatively or additionally, the apparatus is adapted to be implanted inside the body and outside a uterus.
In a preferred embodiment of the invention, where the controller is adapted for a uterus, the controller determines a frequency of contractions in the uterus and wherein said controller electrifies said electrodes responsive to said determined frequency.
Preferably, the electrodes comprise elastic leads.
In a preferred embodiment of the invention, the electrodes are attached to a plurality of remote regions of said uterus.
In a preferred embodiment of the invention, the controller senses and inhibits mechanical activity in substantially the entire uterus. Alternatively or additionally, the controller increases the force of contraction in substantially the entire uterus.
In a preferred embodiment of the invention, the controller is in a capsule adapted to be inserted into a rectum or into a vagina.
Alternatively or additionally, the electrodes are adapted to be implanted inside the body while said controller is adapted to be situated outside the body. Preferably, the electrodes are adapted to be disconnected from said smooth muscle from outside the body.
There is also provided in accordance with a preferred embodiment of the invention, an anastomosis button comprising:
a sleeve portion for joining two portions of a GI tract;
at least two electrodes adapted to be in electrical contact with the GI tract, at either side of the button; and
a controller which electrifies the electrodes to reduce the force of contraction in the GI tract near the button.
Preferably, the controller transmits a pacing signal from the GI tract on one side of the button to the GI tract on the other side of the button.
Alternatively or additionally, reducing the force comprises inhibiting electrical activity of the GI tract at the button.
There is also provided in accordance with a preferred embodiment of the invention, apparatus for inhibiting a returning wave in an intestine, comprises:
at least one electrode for applying an inhibiting electric field to a portion of the intestine;
a sensor which senses the propagation of waves in the intestine; and
a controller which electrifies said electrode responsive to a sensed propagating wave.
Preferably, the sensor detects the returning wave.
There is also provided in accordance with a preferred embodiment of the invention, apparatus for advancing a bolus comprising:
at least one first electrode, for applying an electrical field to a first portion of the GI tract adjacent said bolus;
at least one second electrode, for applying an electric field to a second portion of the GI tract downstream from said bolus; and
a controller which electrifies the at least one first electrode with a non-excitatory field which increases the force of contraction at the first portion and which electrifies the at least one second electrode with a non-excitatory electric field which relaxes the muscle at the second portion.
Preferably, the apparatus comprises an impedance sensor for detecting the existence of a bolus at the first portion of the GI tract.
There is also provided in accordance with a preferred embodiment of the invention, a method of aiding the examination of a GI tract, comprising:
providing an elongated probe, having a tip, inside a portion of a GI tract; and
applying a non-excitatory electric field to the portion of the GI tract adjacent the tip of the probe, which electric field is operative to relax the portion of the GI tract.
Preferably, the method includes inflating the portion of the GI tract after applying said field.
Preferably, the portion of the GI tract is a portion adjacent a bile duct.
There is also provided in accordance with a preferred embodiment of the invention, a method of advancing an elongated probe having a tip and inserted in a portion of the GI tract, comprising:
applying a first electric field at the tip, which field constricts the portion of GI tract to grasp the probe; and
applying a second electric field to a second portion of the GI tract adjacent a portion of the probe distal from the tip, which electric field causes the elongation of the second portion of the GI tract.
Preferably, the method includes applying a third electrical field to a third portion of the GI tract, adjacent portions of the probe distal from the tip, which electrical field relaxes the third portion of the GI tract so that it does not constrict around the probe.
Alternatively or additionally, the method includes applying an inhibitory electric field to block the propagation of activation signals between the first portion and other portions of the GI tract.
There is also provided in accordance with a preferred embodiment of the invention, a method of advancing an elongated probe, comprising:
providing an elongated probe, having a tip, inside a portion of a GI tract; and
applying an excitatory electric field to the portion of the GI tract, which excitatory electric field causes the bowel to transport the probe in a desired direction.
Preferably, the excitatory field is selectively applied either at the tip or at a different location along the probe, distal from the tip, depending on the desired direction of transport.
Alternatively or additionally, the method includes applying an inhibitory electric field, to the portion, to block the propagation of activation signals between the portion and the rest of the GI tract.
In a preferred embodiment of the invention, the probe is an endoscope. Alternatively, the probe is a colonoscope.
There is also provided in accordance with a preferred embodiment of the invention, an elongated probe adapted for advancing in a GI tract, comprising:
an elongated body having a tip;
a plurality of electrodes disposed at least at the tip; and
a controller which selectively electrifies the electrodes to produce non-excitatory electric fields which affect the contraction of smooth muscle.
Preferably, the probe includes a second plurality of electrodes distributed along at least a portion of the body of the probe.
Alternatively or additionally, the controller electrifies said first plurality of electrodes to cause said portion of GI tract to selectively advance or retreat said probe.
Alternatively or additionally, the controller electrifies ones of said first and said second pluralities of electrodes to inhibit the propagation of activation signals from the portion of the GI tract adjacent the tip of the probe to other portions of the GI tract.
There is also provided in accordance with a preferred embodiment of the invention, a method of controlling a uterus, comprising:
determining a portion of the uterus suspected of generating undesirable activation signals; and
applying a local inhibitory electrical field, to the uterus muscle, around the suspected portion.
There is also provided in accordance with a preferred embodiment of the invention, a method of controlling a uterus, comprising:
determining a portion of the uterus suspected of generating undesirable activation signals; and
applying a local desensitizing electrical field to the suspected portion.
There is also provided in accordance with a preferred embodiment of the invention, a method of controlling labor, comprising:
determining a local activation at a plurality of locations of a uterus; and
applying a non-excitatory electric field, to each of the plurality of locations, at a time delay from said local activation time.
Preferably, the non-excitatory field increases the force of contraction at ones of said plurality of locations.
Alternatively or additionally, said non-excitatory field reduces the force of contraction at ones of said plurality of locations.
Alternatively or additionally, the non-excitatory field inhibits the conduction of propagating action potentials across the uterus.
In a preferred embodiment of the invention, the method includes implanting a plurality of electrodes at the plurality of locations. Preferably, the electrodes comprise encapsulated power sources. Alternatively or additionally, the implanting is performed during a cesarean section.
There is also provided in accordance with a preferred embodiment of the invention, a method of aiding birth, comprising applying a non-excitatory electrical field to a birth canal, which non-excitatory field relaxes the birth canal.
There is also provided in accordance with a preferred embodiment of the invention, a method of preventing premature birth, comprising applying a non-excitatory electrical field to a birth canal, which non-excitatory field increases the force of contraction in the birth canal.
There is also provided in accordance with a preferred embodiment of the invention, a method of treating cramps of the uterus, comprising:
detecting electrical or mechanical activity in at least one location of the uterus; and
applying a non-excitatory electrical field at the at least one location.
There is also provided in accordance with a preferred embodiment of the invention, a method of treating cramps, comprising:
providing at least one electrode inside the uterus, which one electrode is in contact with at least a portion of the uterus, at at least one location thereof; and
applying a non-excitatory electrical field to the portion.
In a preferred embodiment of the invention, the non-excitatory field inhibits the propagation of activation signals at the at least one location. Alternatively or additionally, non-excitatory field reduces the force of contraction at the at least one location.
There is also provided in accordance with a preferred embodiment of the invention, apparatus for controlling a smooth muscle, comprising a plurality of individual capsules, each capsule including at least one electrode and a power source which electrifies the electrode, which electrode applies a local non-excitatory field. Preferably, each of said capsules includes a sensor which measures local activity of the smooth muscle.
Alternatively or additionally, the capsules are operative to synchronize the electrification of their electrodes without the meditation of an external controller.
There is also provided in accordance with a preferred embodiment of the invention, apparatus for treating cramps, comprising:
a flexible body having an outside portion and adapted to snugly engage the inside of a uterus;
a plurality of electrodes disposed on the outside of said body; and
a controller which electrifies said electrodes to generate a non-excitatory electrical field.
Preferably, the flexible body is inflatable. Alternatively or additionally, the apparatus includes a second electrode adapted to be placed outside the uterus.
There is also provided in accordance with a preferred embodiment of the invention, a method of controlling a circulatory system, including a heart, comprising:
providing electrodes adjacent a vein; and
electrifying the electrodes to constrict the vein, such that the preload on the heart is increased.
There is also provided in accordance with a preferred embodiment of the invention, a method of controlling a circulatory system, including a heart, comprising:
providing electrodes adjacent a vein; and
electrifying the electrodes to expand the vein, such that the preload on the heart is reduced.
There is also provided in accordance with a preferred embodiment of the invention, a method of controlling a circulatory system, including a heart, comprising:
providing electrodes adjacent an artery; and
electrifying the electrodes to constrict the artery, such that the afterload on the heart is increased.
There is also provided in accordance with a preferred embodiment of the invention, a method of controlling a circulatory system, including a heart, comprising:
providing electrodes adjacent an artery; and
electrifying the electrodes to expand the artery, such that the afterload on the heart is reduced.
There is also provided in accordance with a preferred embodiment of the invention, a method of controlling vascular spasm, in a circulatory system having a heart, comprising:
determining a vessel in spasm, which results in an abnormally constricted lumen; and
applying a non-excitatory electric field to the vessel, which field causes the lumen to expand.
It should be appreciated that two or more of the above methods of controlling the circulatory system may also be practiced together.
In a preferred embodiment of the invention, the method includes applying a non-excitatory electric field to at least a portion of the heart.
There is also provided in accordance with a preferred embodiment of the invention, apparatus for controlling a circulatory system having a heart, comprising:
a plurality of electrodes disposed about at least one major blood vessel;
a blood pressure sensor which measures blood pressure; and
a controller which electrifies the plurality of electrodes responsive to the measured blood pressure.
Preferably, the apparatus includes an external control which activates said controller.
Alternatively or additionally, the apparatus includes an ECG sensor which detects the cardiac rhythm. Alternatively or additionally, the controller relaxes said blood vessel to reduce the blood pressure. Alternatively or additionally, the controller contracts said blood vessel to increase the blood pressure.
There is also provided in accordance with a preferred embodiment of the invention, a method of controlling the output of a gland, comprising:
providing at least one electrode near the gland; and
applying a non-excitatory electric field to the gland.
Preferably, the non-excitatory electric field inhibits the activity of hormone producing cells in the gland. Alternatively or additionally, the non-excitatory electric field is a substantially DC field. Preferably, the method includes periodically changing the polarity of the field. Preferably, one polarity is applied for a significantly larger portion of the time.
In a preferred embodiment of the invention, the gland is a pancreas. Preferably, the method includes monitoring a level of glucose in the blood, wherein applying said electric field comprises applying said field responsive to said monitored level.
There is also provided in accordance with a preferred embodiment of the invention, apparatus for controlling the output of a gland, comprising:
a sensor for measuring a level of a chemical in a blood stream;
at least one electrode adjacent said gland; and
a controller which electrifies said electrode with a non-excitatory electric field, responsive to the measured level.
Preferably, the chemical is glucose. Alternatively or additionally, the apparatus is completely implantable.
There is also provided in accordance with a preferred embodiment of the invention, a method of controlling the activation profile of a smooth muscle organ, comprising:
determining a desired activation profile for the organ; and
applying at least one non-excitatory field to a portion of the organ to modify its activation profile.
Preferably, the activation profile comprises a mechanical activation profile.
In a preferred embodiment of the invention, the method includes:
measuring a tension in the smooth muscle; and
modifying the application of the non-excitatory field responsive to the measured tension.
Alternatively or additionally, the method includes:
measuring a pressure in the smooth muscle; and
modifying the application of the non-excitatory field responsive to the measured pressure.
Alternatively or additionally, the method includes applying at least one excitatory electric field to the smooth muscle.
Alternatively or additionally, the method includes applying a non-excitatory field comprises applying an inhibitory electric field to the muscle.
Alternatively or additionally, applying a non-excitatory field comprises applying an electric field which reduces the force of contraction in the muscle.
Alternatively or additionally, applying a non-excitatory field comprises applying an electric field which increases the force of contraction in the muscle.
Preferably, the organ is a stomach. Alternatively or additionally, the organ is a small intestine. Alternatively or additionally, the organ is a large intestine. Alternatively or additionally, the organ is a uterus.
There is also provided in accordance with a preferred embodiment of the invention, apparatus for dictating a mechanical activation profile to a smooth muscle organ, comprising:
at least three electrodes, adapted to be distributed over the organ;
at least one sensor which senses local mechanical activity of the organ; and
a controller which electrifies selected ones of said electrodes, responsive to the sensed local mechanical activity, to dictate a particular activation profile to the organ.
Preferably, the organ is a uterus and wherein the activation profile is a pattern of contraction during labor.
Although many embodiments of the present invention are described herein mainly as methods, it should be appreciated that the scope of the invention includes apparatus adapted to perform these methods. In particular, the scope of the invention includes programmable electric field generators which are programmed to supply an electric field in accordance with a preferred embodiment of the invention. In a preferred embodiment of the invention, programmable variables include, waveforms, amplitudes, frequencies, durations, delays, synchronization and response to locally measured parameters of muscle activity. It should be appreciated that the behavior of a muscle in one portion thereof can be modified by applying an electric field to a second portion thereof, for example, by inhibiting the propagation of an activation signal to the one portion or by changing the layout of forces acting on the one portion.